Der Vermis Matrizen – Converting d20 to d100
Converting d20 to d100 in Classic Games & Retro Clones
The d20 tables used in classic games and retro clones can be easily converted to d100. One reason for doing this is that each pip of a d20 conceals 5% within it and converting the value to d100 makes the hidden numbers between 1% and 5% available for use if you apply modifiers or construct other tables to take advantage of it.
The known mechanic for a d20 table is that one must roll equal to or greater than the number to succeed. That is if 15 is indicated as the target number you are required to roll 15 or better using d20 and may add +1 or more to the dice roll in the form of dice roll modifiers. This mechanic is easily comprehended which helps explain its popularity. It also conceals the actual nature of the chance of success for were I to tell the reader the chance of success is only 6/20, or 30%, it would be difficult to believe without doing the math; few like to do the math.
In order to follow same mechanic for d100 we have to convert the values of d20 in such a way as to make possible rolling equal to the target number or better. The following table converts d20 values to d100. The 5% formerly hidden in the number 1 is now broken down to a range; 01, 02, 03, 04, and 05. This is true of each pip of the dice.
|
d20
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
|
d100
|
01
|
06
|
11
|
16
|
21
|
26
|
31
|
36
|
41
|
46
|
|
d20
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
19
|
20
|
|
d100
|
51
|
56
|
61
|
66
|
71
|
76
|
81
|
86
|
91
|
96
|
Once we have the d100 values, how do we then apply them? In the following d100 Attack Matrix the player must roll equal to or greater than the target number. A +1 bonus equates to a +5% added to the dice roll.
|
Character’s
Level |
Defender’s
Armour Class |
||||||||||||
|
9
|
8
|
7
|
6
|
5
|
4
|
3
|
2
|
1
|
0
|
-1
|
-2
|
-3
|
|
|
Normal
Man |
51
|
56
|
61
|
66
|
71
|
76
|
81
|
86
|
91
|
96
|
96
|
96
|
96
|
|
1st
to 3rd |
46
|
51
|
56
|
61
|
66
|
71
|
76
|
81
|
86
|
91
|
96
|
96
|
96
|
|
4th
+ Higher |
36
|
41
|
46
|
51
|
56
|
61
|
66
|
76
|
81
|
86
|
91
|
96
|
96
|
There are some interesting potential applications for d100 vis-a-vis role playing as Characters might seek training with a martial arts master for example and become skilled with a particular weapon. This would grant attack benefits of +1% through +5% as the training progresses for a fee of course, or performing tasks for the master.
Magical weapons might also have ranges of values below the standard 5% benefit, or these may apply to different creatures or classes of creatures, +5% for some, +1% for others. For example, a magical sword which is +5% vs. the living dead but possibly +3% vs. a certain type, and +1% vs. something really nasty.
